6龄黏虫幼虫受球孢白僵菌侵染后生长发育及体内成瘤反应的变化

李平 江幸福 孟令贺 程云霞 张蕾 翟保平

摘要 為探讨黏虫被球孢白僵菌侵染后生长发育情况及其体内的免疫反应，设置孢子浓度为104、5×104、105、5×105、106个/mL及5×106个/mL的球孢白僵菌菌液注射黏虫6龄初幼虫，研究球孢白僵菌对黏虫校正死亡率、羽化率、蛹重等生长发育指标的影响以及成瘤反应的浓度依赖效应。结果表明，6龄幼虫的校正死亡率随菌液浓度升高而逐渐增加。蛹重随菌液浓度增加而下降，但仅在106、5×106个/mL浓度处理时蛹重显著低于对照。同时，在孢子浓度为5×105、106、5×106个/mL时羽化率较对照显著降低，雌雄成虫寿命也显著缩短，而6龄幼虫至成虫羽化的发育历期在105、5×105、106、5×106个/mL浓度处理时较对照显著延长。此外，白僵菌侵染诱发黏虫免疫成瘤反应，并且具有明显的时间和浓度效应。注射84 h内，黏虫体内成瘤的数量随注射时间延长而递增，其后不再增加;同时，成瘤数量随着菌液浓度升高而增加，至106个/mL浓度时不再显著上升。该结果为揭示黏虫抵抗真菌侵染的免疫防御机制以及所产生的免疫代价提供了科学依据。

关键词 黏虫; 白僵菌; 生长发育; 成瘤

中图分类号： S 433.4

文献标识码： A

DOI： 10.16688/j.zwbh.2020560

Changes in the development and nodule formation of the 6th-instar

Mythimna separata larvae after infection by Beauveria bassiana

LI Ping1，2， JIANG Xingfu2， MENG Linghe2， CHENG Yunxia2， ZHANG Lei2*， ZHAI Baoping1*

（1. College of Plant Protection，Key Laboratory of Integrated Management of Crop Disease and Pests，Ministry of

Education，Nanjing Agricultural University，Nanjing 210095， China;  2. State Key Laboratory for Biology of Plant

Disease and Insect Pests，Institute of Plant Protection，Chinese Academy of Agricultural Sciences， Beijing 100193，China）

Abstract

In order to explore the effects of Beauveria bassiana on the growth and development of Mythimna separata and its induction of immune response， the spore concentration was set to 104， 5×104， 105， 5×105， 106 and 5×106 spores/mL， respectively. The 6th-instar larvae of M.separata were injected with Beauveria bassiana spore suspensions to study the effects of B.bassiana on the growth and developmental indicators such as corrected mortality， emergence rate， pupa weight， and the injection concentration-dependent effect of nodule formation. The results showed that the corrected mortality of the 6th-instar larvae increased with increasing injection concentration. Pupa weight decreased with increasing injection concentration， but decreased significantly at the concentrations of 106 and 5×106 spores/mL. At the same time， the emergency rate decreased significantly with the increase of treatment concentration only under the concentration of 5×105， 106， 5×106 spores/mL. The life spans of male and female adults were also significantly shortened. The developmental duration from the 6th-instar larvae to emergency was significantly longer than that of the control at the concentration of 105 spores/mL and above. In addition， infection by B.bassiana induced immune responses of M.separata with significant time and concentration effects. Within 84 h after injection， the number of nodules increased with time， but did not increase significantly thereafter. In addition， the number of nodules increased with increasing fungal liquid concentration， but the number of nodules did not increase significantly when the concentration reached 106 spores/mL. The results provide a scientific basis for revealing the immune defense mechanism of M.separata against fungal infection and immune cost.

Key words

Mythimna separata; Beauveria bassiana; development; nodule formation

病原真菌进入昆虫体内会受到寄主免疫系統的识别和抵抗[1-2]。昆虫的免疫系统是一个完整地存在于开放血淋巴系统的防御体系，通常由血浆中抗菌肽、溶菌酶、酚氧化酶等活性因子参与的体液免疫系统以及多种功能的血细胞参与的细胞免疫系统组成[3-4]。其中昆虫的细胞免疫主要依赖血细胞对外来抗原或异物的吞噬、集结和包囊作用，所以昆虫体内血细胞的数量、微聚成瘤等反应可作为判断昆虫免疫力的主要指标[5-7]。……